1. Field of the Invention
The present general inventive concept relates to an electrophotographic image forming apparatus to improve an assembly precision of a developing cartridge with respect to a main frame.
2. Description of the Related Art
A conventional electrophotographic image forming apparatus such as a laser printer, a facsimile, a digital copy machine, etc., scans a light to a photosensitive medium charged to a predetermined electric potential to form an electrostatic latent image, develops the latent image with a predetermined colored toner, and transfers and fuses the developed image to a printing medium to print the image.
Referring to FIGS. 1 and 2, a conventional image forming apparatus includes a main frame 1 formed by means of an injection molding for reducing a number of assembling processes and lowering a manufacturing cost, and a developing cartridge 10 slidably coupled to the main frame 1. Here, the developing cartridge 10 includes components such as a developer, a developing roller, a supplying roller, a regulating blade, etc., therein. Here, the main frame 1 is manufactured out of a resin frame by the injection molding for improving productivity and reducing the manufacturing cost, or a metal frame by a press type for reducing a mold manufacturing and improving stability of an electrical connection.
Also, the components of the developing cartridge 10 are supplied with power from a high voltage source (not illustrated) disposed to the main frame 1 for performing a developing process. For this, electrodes 3 and 13 are formed to facing positions of the main frame 1 and the developing cartridge 10, and are electrically connected with each other when the developing cartridge 10 is coupled to the main frame 1.
If the main frame 1 manufactured out of the resin or the metal, and the developing cartridge 10 are manufactured, there exists a design tolerance. That is, if there is a tolerance in a direction of arrow A illustrated in FIG. 2 in the main frame 1 and the developing cartridge 10, the tolerance has an effect on mounting of the developing cartridge 10.
For example, as illustrated by an alternate long and short dash line in FIG. 2, if the developing cartridge 10 is designed to meet a lower limit in design tolerance and the main frame 1 is designed to meet an upper limit in design tolerance, there exists a gap between the main frame 1 and the developing cartridge 10 so that an electrical connection inferiority between the electrodes 3 and 13 can be caused. Accordingly, power is unstably supplied to the developing cartridge 10, thereby causing a print inferiority.
In contrast, if the developing cartridge 10 is designed to meet an upper limit in design tolerance and the main frame 1 is designed to meet a lower limit in design tolerance, the developing cartridge 10 is incapable of being normally mounted to the main frame 1, or being smoothly mounted to the main frame 1.
Also, a gear 15 inside the developing cartridge 10 is incapable of being smoothly engaged with a gear 5 mounted to the main frame 1. Accordingly, the developing cartridge 10 vibrates in an operation of the developing cartridge 10, thereby causing an image inferiority such as a jitter.